Method for applying markings and signs on a surface

ABSTRACT

Method for applying markings or signs to a surface (1), such as road surfaces and the like, comprising the laying down of a layer of a heated mass of a thermoplastic material (3). Before the laying down of thermoplastic material (3) there is applied a primer layer (2) on the surface (1), consisting of a curable plastic material which comprises two or more components.

This invention relates to the application of markings or signs on asurface, in particular road surfaces and the like. Other and similarsurfaces which may be of interest in this connection, are for exampleindustry floors which in certain cases are subjected to correspondingstresses and wear as roads.

For road markings for example in the form of edge lines, a gooddurability and long lifetime is desired, so that the expenses related tomarking can be kept as low as possible. In addition to the direct wearresulting from car traffic, in particular with studded tires, it is alsoa great problem to obtain sufficient adhesion between the markingapplied and the actual road suface. This is a problem that is ratheraccentuated when concrete pavements of high strength are concerned, butalso other forms of road pavement, such as meagre or stone-rich asphaltpavements, i.e. asphalt pavements having a small content of bitumen. Thedifficulties of a good and durable adhesion is related to, inter alia,that water and moisture can penetrate into the road surface and from theunderside weaken the adhesion of applied markings.

There are previously known a number of different methods and materialsfor use in such road marking and the like. U.S. Pat. No. 4,102,718relates to a road marking material in tape form, which incorporates aprimer layer of a thermoplastic material, which beforehand is bonded tothe actual marking tape before being laid down on the road surface. Asan initial step the road surface may be prepared with a wetting agent.

Norwegian patent 122.385 is more interesting since to a large extent itaddresses the adhesion of a road marking mass being laid down on theroad surface. There is however the question of sulphurous masses, whichare not of any interest in the present connection. At the end of thepatent specification it is mentioned briefly that priming can beapplied, but without any closer discussion of the type of primingmaterial.

As further examples of prior art of more remote interest, reference canbe made to Norwegian patent 122.602 and Norwegian published patentapplication 126.029, Swedish published patent application 341.874,European patent application 0397.406 and U.S. Pat. No. 4,708,518. Thelatter patent specification is related to the above mentioned U.S.patent. It is to be noted that the Swedish patent publication referredto, in addition to a thermoset plastic as road marking material, alsodescribes thermoplastic materials. The present invention takes as astarting point a method comprising the laying down of a layer of aheated mass of a thermoplastic material. The composition of such a knownand typical thermoplastic material for this purpose, is as follows:

thermoplastic binder minimum 15%

pigment (white) maximum 8%

glass pearls 0-40%

filler (sand/limestone powder) ad. 100%

This typical road marking mass based on thermoplastic materials resultin wear resistant and durable lines and the material hardens in secondsupon being laid down, so that for example car traffic can quickly run asnormal afterwards without any risk of damages to cars or marking lines.Moreover it is important to remark that such a mass on a thermoplasticbases does not contain solvents or other substances that may bedetrimental to health or environment. The mass can be laid out in athickness from 1-6 mm.

According to the invention it has surprisingly been found thatsubstantially improved results are obtained by applying a primer layerto the surface before laying down a heated mass of thermoplasticmaterial, whereby the primer layer consists of a curable plasticmaterial comprising two or more components.

As a curable plastic material to be employed here, there are severalpossible types, for example polyurethane. This because, inter alia,polyurethane is heat curable, so that the hardening of such a primerlayer to a substantial degree will be provided for by the immediatelyfollowing and superposed layer of heated thermoplastic material. Thusthe heat being given off from the heated road marking mass makes itunnecessary to provide for any specific drying or curing time for theprimer layer, so that the pre-treatment with primer and the laying downof the actual road marking mass can take place in substantiallysimultaneous operations provided for by one and the same machine.

The method according to the invention is particularly advantageous whenemploying an epoxy plastic as the heat curable plastic material in theprimer layer. This material leads to a particularly efficientimpregnation or sealing of the road surface and the small pores ordepressions occuring therin, so that water penetration is prevented andthere is obtained a very good adhesion. Compared to usual primer typesfor various purposes, which only give a rather superficial adhesion toroad surfaces of interest, an epoxy primer layer in combination with thethermoplastic road marking mass has proved to be unexpectedlyadvantageous.

In the following description the invention will be explained moreclosely with reference to the drawings, wherein:

FIG. 1 shows a schematic cross section through the surface of a roadpavement with an applied road marking, and

FIG. 2 highly simplified shows a mobile equipment for carrying out themethod according to the invention.

FIG. 1 shows a part of a road surface 1, which can be for example anasphalt pavement with irregularities or pores as indicated. At thesurface there is in the first place applied a primer layer 2 whichpreferably is a heat curable epoxy plastic based on two or morecomponents, being sprayed onto the road surface 1 in a suitable widthfor the subsequent laying down of the actual road marking mass 3 basedon a suitable thermoplastic material. It is obvious that FIG. 1 showsboth the primer layer 2 and the road marking mass 3 at a highlyexaggerated thickness as seen in relation to the other dimensions.

The preferably heat curable primer layer 2 is applied advantageously ata thickness from 0.05-0.4 mm, whereas the thermoplastic mass 3 is laiddown at a thickness being preferably within the range 0.4-6 mm. Inactual practice such a combination has been found to be very favorable.

FIG. 2 illustrates a possible form of laying equipment being mobile on atruck 20. At the underside thereof between the front and rear wheels,there is provided a first spraying or dosing device 11 for the primermaterial, that can be supplied from a two-part tank 16,17, for thepolymer component and the curing component respectively, in the case ofa two-component material being employed. In the second place there ismounted a laying or dosing device 12 for the thermoplastic materialsupplied from a tank or pot 18 where this material is heated to asuitable temperature, such as within the range 150-230° C.

For the purpose of an efficient and safe performance of the methoddescribed above, the first and the second device 11 and 12 are mutuallyalined in the driving direction and at a spacing resulting in afavourable time relationship between the delivery of primer andthermoplastic material respectively. In practice the driving speed maybe from 3-4 to 20 km/h.

In order to provide for a sufficiently short curing time for primerlayer 2, it is possible in a manner known per se, to add an acceleratoragent to the curing component in tank part 17. Moreover according to theinvention it can be expedient to add a pigment to the primer compositiondelivered from dosing device 11, so as to give a desired colouring ofthe primer layer, for example white, so that the very resistant primerlayer 2 (see FIG. 1) can constitute a "pre-marking" for road marking anext time when the actual road marking layer 3 has been more or lessworn away.

Furthermore at the front of the truck 20 there is mounted a forwardlyprojecting arm 15A which carries a heating device 15, for example on thebasis of gas heating, facing downwards towards the road surface. Withsuch pretreating of the pavement a good road marking can be secured evenunder difficult conditions, such as cold weather or when there is rain.Such heating will be able to dry up the road surface to a significantdegree during or after rain and at the same time heat up the surfacesomewhat, which is of particular interest on cold days. In summer heatthe temperature of a road pavement of asphalt or concrete can reach 50°C. and it is then not required to use any heating device 15. Nor isthere any need in such case for curing heat from the thermoplastic mass,for curing the primer layer. A particular effect of the heating device15 is that the road surface is oxydized to a certain, desired degree andbesides that a wax layer occuring at the surface of newly cast concretepavements, is burnt away. This is also favorable for the desiredadhesion of the road marking with the combination of a primer layer anda thermoplastic material as explained above.

Although there are types of heat curable plastic materials for theprimer layer, that tolerate water to some degree, heating by means ofthe device 15 when marking road surfaces in rain, will be advantageous.

The method of road marking as described here, is secure, efficient andquick at the same time as there is obtained a wear-resistant markingwith good adhesion properties. It is important that the markingoperation can be done quickly, because road marking must often takeplace while the traffic on the road concerned, at least partially mustcontinue, so that known methods may be more problematic in the case,inter alia, of employing usual primer types which require a good dryingtime or a specific after-treatment before the actual road marking massis applied.

What is claimed is:
 1. A method for applying markings or signs on asurface, comprising the steps ofapplying to the surface a primer layercomprising an uncured plastic material comprising two or morecomponents, laying down on the primer layer a heated mass comprising athermoplastic material, and initiating the curing of the primer layer bythe heat of the heated mass of thermoplastic material.
 2. The methodaccording to claim 1, wherein the uncured plastic material is an epoxyresin comprising an epoxy component and a hardener component.
 3. Themethod according to claim 1, wherein the primer layer further comprisesa pigment.
 4. The method according to claim 1, wherein the primer layeris applied in a thickness of 0.05-0.4 mm.
 5. The method according toclaim 1, wherein the heated mass of thermoplastic material is laid downin a thickness of 0.4-6 mm.
 6. The method according to claim 1, furthercomprising the step of heating the surface before applying the primerlayer to the surface below a primer curing temperature.